Kasane Teto is a character, which was created as a fake "Vocaloid" initially.
Following the rising popularity of Hatsune Miku, which was released in August 2007, vip@2ch users collectively planned the troll "new Vocaloid release" for the April Fool's day of 2008, and fake demos were posted on Nicovideo. The illustration was created by Sen and the songs were sung by Mayo Oyamano.
After the troll, Mayo's voice was recorded for the vocal synthesis program Vocal Synthesizer Tool UTAU, which was developed by Ameya/Ayame. Soon many professional and amateur musicians started to compose songs using this newcomer, and Teto established popularity both on Nicovideo and YouTube.
Kasane Teto is not a fake diva any longer. The popularity led to 3D models, figurines and many illustrations by fans. Furthermore, the regular updating of the voicebank and UTAU platform has made Teto one of the comparable characters to Vocaloids.
